The present invention relates generally to wireless communications, and more particularly, to exploiting cell dormancy and load balancing in long term evolution LTE heterogenous networks (HetNets).
Cellular wireless networks are morphing into dense hetergenous networks HetNets formed by a multitude of transmission points (TPs or nodes) ranging from the more conventional high power macro base-stations to low power pico nodes, all deployed in a highly irregular fashion. Realizing the full potential of these HetNets via intelligent resource management has become a major driver of both academic and industrial research. Resource management in HetNets is done over a coordination area comprising of a set of transmission points (TPs) and a set of users that those TPs should serve. The design of such resource management (or allocation) schemes commenced by assuming ideal conditions, such as availability of perfect and instantaneous channel state information (CSI) for all TP-user links in the coordination area. Instantaneous data sharing among the TPs was generally not assumed and most works adopted a pre-determined association of users to TPs over the time-scale of interest. However, the design of the resulting optimal resource allocation scheme was shown to be intractable in general. Consequently, research efforts were directed towards obtaining efficient and near-optimal scheme. Non-idealities in the CSI were also explicitly modeled and incorporated. In addition, methods that account for the overhead (corresponding to training and over-the-air and backhaul signaling) have been proposed and analyzed. A state-of-the-art scheme which accounts for several practical limitations is described in, wherein each user also aids the network via smart feedback.
Most existing works in this area consider either exploiting only cell dormancy for a given user association or exploiting only user association for a given set of active transmission nodes. Moreover, prior efforts do not realize that the user association problem is optimally solvable in an efficient manner.
The focus of this invention is on heterogeneous wireless networks (HetNets) that are expected to be fairly common and where the transmission points in the HetNet will be connected to each other by a non-ideal backhaul with a relatively high latency (ranging from 50 milliseconds to several dozens of milliseconds). Over such HetNets schemes that strive to obtain all coordinated resource management decisions within the fine slot-level granularity (typically a millisecond) are not suitable, since coordination (which involves exchange of messages and signaling over the backhaul) cannot be performed in such a fast manner